\chapter{Hardware}  % -----------------------------------------------------------------------------


\section{Adjustable periscopes}  % ----------------------------------------------------------------


Our light sources take on horizontal or vertical polarizations according to which tuning process is
used.  %
Our experiments are opinionated about polarization, so some strategy for aligning polarization is
necessary.  %
Desire fully reflective, easy to switch without changing path length (delay) etc... For several
years, we used brewster-angle polarization unifiers...  %
These worked by...  %
But these were very difficult to align, and they were too lossy for some of the weaker tuning
processes.  %
As an alternative, we designed a more traditional periscope with adjustability for our unique
needs.  %


\subsection{Alignment}  % -------------------------------------------------------------------------


\begin{enumerate}
  \item in flipped polarization:
    \begin{itemize}
      \item stage near
      \item upper mirror far
    \end{itemize}
  \item in kept polarization:
    \begin{itemize}
      \item stage x and upper mirror height near
      \item lower mirror far
    \end{itemize}
\end{enumerate}